Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see
Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/go/cfn. An account on Cisco.com is not required.

Information About IPv6 Routing: Multiprotocol BGP Extensions for IPv6

Multiprotocol BGP Extensions for IPv6

Multiprotocol BGP is the supported exterior gateway protocol (EGP) for IPv6. Multiprotocol BGP extensions for IPv6 supports many of the same features and functionality as IPv4 BGP. IPv6 enhancements to multiprotocol BGP include support for an IPv6 address family and network layer reachability information (NLRI) and next hop (the next router in the path to the destination) attributes that use IPv6 addresses.

Configuring an IPv6 BGP Routing Process and BGP Router ID

Perform this task to configure an IPv6 BGP routing process and an optional BGP router ID for a BGP-speaking device.

BGP uses a router ID to identify BGP-speaking peers. The BGP router ID is 32-bit value that is often represented by an IPv4 address. By default, the router ID is set to the IPv4 address of a loopback interface on the device. If no loopback interface is configured on the device, then the software chooses the highest IPv4 address configured to a physical interface on the device to represent the BGP router ID.

When configuring BGP on a device that is enabled only for IPv6 (the device does not have an IPv4 address), you must manually configure the BGP router ID for the device. The BGP router ID, which is represented as a 32-bit value using an IPv4 address syntax, must be unique to the BGP peers of the device.

Disables the IPv4 unicast address family for the BGP routing process specified in the previous step.

Note

Routing information for the IPv4 unicast address family is advertised by default for each BGP routing session configured with the
neighborremote-as command unless you configure the
nobgpdefaultipv4-unicast command before configuring the
neighborremote-as command.

Step 5

bgprouter-idip-address

Example:

Device(config-router)# bgp router-id 192.168.99.70

(Optional) Configures a fixed 32-bit router ID as the identifier of the local device running BGP.

Configuring IPv6 Multiprotocol BGP Between Two Peers

By default, neighbors that are defined using the
neighborremote-as command in router configuration mode exchange only IPv4 unicast address prefixes. To exchange other address prefix types, such as IPv6 prefixes, neighbors must also be activated using the
neighboractivate command in address family configuration mode for the other prefix types, as shown for IPv6 prefixes.

Adds the IPv6 address of the neighbor in the specified autonomous system to the IPv6 multiprotocol BGP neighbor table of the local device.

Step 5

address-familyipv6[unicast |
multicast]

Example:

Device(config-router)# address-family ipv6

Specifies the IPv6 address family and enters address family configuration mode.

The
unicast keyword specifies the IPv6 unicast address family. By default, the device is placed in configuration mode for the IPv6 unicast address family if a keyword is not specified with the
address-familyipv6 command.

The
multicast keyword specifies IPv6 multicast address prefixes.

Step 6

neighbor {ip-address |
peer-group-name |
ipv6-address%}
activate

Example:

Device(config-router-af)# neighbor 2001:DB8:0:CC00::1 activate

Enables the neighbor to exchange prefixes for the IPv6 address family with the local device.

Advertising Routes into IPv6 Multiprotocol BGP

By default, networks that are defined in router configuration mode using the
network command are injected into the IPv4 unicast database. To inject a network into another database, such as the IPv6 BGP database, you must define the network using the
network command in address family configuration mode for the other database, as shown for the IPv6 BGP database.

The
unicast keyword specifies the IPv6 unicast address family. By default, the device is placed in configuration mode for the IPv6 unicast address family if a keyword is not specified with the
address-familyipv6 command.

Advertises (injects) the specified prefix into the IPv6 BGP database. (The routes must first be found in the IPv6 unicast routing table.)

Specifically, the prefix is injected into the database for the address family specified in the previous step.

Routes are tagged from the specified prefix as "local origin."

The
ipv6-prefixargument in the
network command must be in the form documented in RFC 2373 where the address is specified in hexadecimal using 16-bit values between colons.

The
prefix-length argument is a decimal value that indicates how many of the high-order contiguous bits of the address comprise the prefix (the network portion of the address). A slash mark must precede the decimal value.

Step 6

exit

Example:

Device(config-router-af)# exit

Exits address family configuration mode, and returns the device to router configuration mode.

Repeat this step to exit router configuration mode and return the device to global configuration mode.

Configuring a Route Map for IPv6 Multiprotocol BGP Prefixes

By default, neighbors that are defined using the
neighborremote-as command in router configuration mode exchange only IPv4 unicast address prefixes. To exchange other address prefix types, such as IPv6 prefixes, neighbors must also be activated using the
neighboractivate command in address family configuration mode for the other prefix types, as shown for IPv6 prefixes.

By default, route maps that are applied in router configuration mode using the
neighborroute-map command are applied to only IPv4 unicast address prefixes. Route maps for other address families must be applied in address family configuration mode using the
neighborroute-map command, as shown for the IPv6 address family. The route maps are applied either as the inbound or outbound routing policy for neighbors under the specified address family. Configuring separate route maps under each address family type simplifies managing complicated or different policies for each address family.

The
unicast keyword specifies the IPv6 unicast address family. By default, the device is placed in configuration mode for the IPv6 unicast address family if the
unicast keyword is not specified with the
address-familyipv6 command.

The
multicast keyword specifies IPv6 multicast address prefixes.

Step 6

neighbor {ip-address |
peer-group-name |
ipv6-address%}
activate

Example:

Device(config-router-af)# neighbor 2001:DB8:0:cc00::1 activate

Enables the neighbor to exchange prefixes for the IPv6 address family with the local device using the specified link-local addresses.

Changes to the route map will not take effect for existing peers until the peering is reset or a soft reset is performed. Using the
clearbgpipv6 command with the
soft and
in keywords will perform a soft reset.

Step 8

exit

Example:

Device(config-router-af)# exit

Exits address family configuration mode, and returns the device to router configuration mode.

Distributes any routes that have a destination IPv6 network number address permitted by a prefix list, or performs policy routing on packets.

Redistributing Prefixes into IPv6 Multiprotocol BGP

Redistribution is the process of redistributing, or injecting, prefixes from one routing protocol into another routing protocol. This task explains how to inject prefixes from a routing protocol into IPv6 multiprotocol BGP. Specifically, prefixes that are redistributed into IPv6 multiprotocol BGP using the
redistribute router configuration command are injected into the IPv6 unicast database.

The
unicast keyword specifies the IPv6 unicast address family. By default, the device is placed in configuration mode for the IPv6 unicast address family if a keyword is not specified with the
address-familyipv6 command.

Redistributes IPv6 routes from one routing domain into another routing domain.

Step 6

exit

Example:

Device(config-router-af)# exit

Exits address family configuration mode, and returns the device to router configuration mode.

Repeat this step to exit router configuration mode and return the device to global configuration mode.

Clearing External BGP Peers

SUMMARY STEPS

1.enable

2.clearbgpipv6 {unicast |
multicast}
external [soft] [in |
out]

3.clearbgpipv6 {unicast |
multicast}
peer-groupname

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Device> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2

clearbgpipv6 {unicast |
multicast}
external [soft] [in |
out]

Example:

Device# clear bgp ipv6 unicast external soft in

Clears external IPv6 BGP peers.

Step 3

clearbgpipv6 {unicast |
multicast}
peer-groupname

Example:

Device# clear bgp ipv6 unicast peer-group marketing

Clears all members of an IPv6 BGP peer group.

Advertising IPv4 Routes Between IPv6 BGP Peers

If an IPv6 network is connecting two separate IPv4 networks, IPv6 can be used to advertise the IPv4 routes. Configure the peering using the IPv6 addresses within the IPv4 address family. Set the next hop with a static route or with an inbound route map because the advertised next hop will usually be unreachable. Advertising IPv6 routes between two IPv4 peers is also possible using the same model.

Changes to the route map will not take effect for existing peers until the peering is reset or a soft reset is performed. Using the
clearbgpipv6 command with the
soft and
in keywords will perform a soft reset.

Step 9

exit

Example:

Device(config-router-af)# exit

Exits address family configuration mode, and returns the device to router configuration mode.

Example: Advertising Routes into IPv6 Multiprotocol BGP

The following example injects the IPv6 network 2001:DB8::/24 into the IPv6 unicast database of the local device. (BGP checks that a route for the network exists in the IPv6 unicast database of the local device before advertising the network.)

Example: Redistributing Prefixes into IPv6 Multiprotocol BGP

Example: Advertising IPv4 Routes Between IPv6 Peers

The following example advertises IPv4 routes between IPv6 peers when the IPv6 network is connecting two separate IPv4 networks. Peering is configured using IPv6 addresses in the IPv4 address family configuration mode. The inbound route map named rmap sets the next hop because the advertised next hop is likely to be unreachable.

MIBs

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/go/cfn. An account on Cisco.com is not required.

Multiprotocol BGP Extensions for IPv6 supports the same features and functionality as IPv4 BGP.

Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL:
www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.